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Biomedical subjects

C Kennedy

Publications and source records attributed to C Kennedy.

At least 19 recordsLinked to original sources
PubMed1992

Properties of the nuclear P1 protein, a mammalian homologue of the yeast Mcm3 replication protein.

Polyclonal antibodies were raised against a multiprotein 'holoenzyme' form of calf thymus DNA polymerase alpha-primase and used to probe a human cDNA-protein expression library constructed in the lambda gt11 vector. The probe identified a series of cDNA clones derived from a 3.2 kb mRNA which encodes a novel 105 kDa polypeptide, the P1 protein. In intact cells, the P1 protein was specifically associated with the nucleus, and in cell extracts, it was associated with complex forms of DNA polymerase alpha-primase. The synthesis of human P1-specific mRNA was stimulated upon addition of fresh serum to growth-arrested cells, and RNA blot analyses with the human P1-cDNA probe indicated that P1 is encoded by a strictly conserved mammalian gene. The amino acid sequence deduced from a 240-codon open reading frame resident in the largest human P1-cDNA (0.84 kb) displayed greater than 96% identity with that deduced from the equivalent segment of a 795-codon open reading frame of a larger mouse P1-cDNA (2.8 kb). Throughout its length, the primary structure of mammalian P1 displayed strong homology with that of Mcm3, a 125 kDa yeast protein thought to be involved in the initiation of DNA replication (Gibson et al. 1990. Mol. Cell. Biol. 10: 5707-5720). The P1-Mcm3 homology, the strong conservation of P1 among mammals, its nuclear localization, and its association with the replication-specific DNA polymerase alpha strongly suggest an important role of the P1 protein in the replication of mammalian DNA.

Amino Acid Sequence↗
PubMed1992

Sensory testing in human immunodeficiency virus type 1-infected men. HIV Neurobehavioral Research Center Group.

Patients with acquired immunodeficiency syndrome frequently suffer peripheral neuropathy. We investigated its prevalence and relationship to clinical stage of human immunodeficiency virus (HIV) infection using quantitative sensory testing and nerve conduction testing. Vibratory threshold was determined in the right great toe and index finger of 179 men seropositive for HIV (28 with acquired immunodeficiency syndrome [AIDS] or AIDS-related complex [ARC], 151 asymptomatic) and 32 HIV-seronegative controls. None had clinical peripheral neuropathy. Abnormal threshold was control mean plus 2.5 SDs. In the toe, 10 (36%) of 28 subjects with AIDS or ARC had abnormal vibratory thresholds, compared with seven (5%) of 151 asymptomatic seropositive subjects and none of 32 controls. A subgroup of 168 seropositive subjects underwent nerve conduction testing. Abnormality rates were similar, but abnormalities of nerve conduction coincided with quantitative sensory testing abnormalities in only half the cases. Mean (+/-SD) vibratory threshold was significantly greater in subjects with AIDS or ARC (3.00 +/- 0.51 vibratory units) than in asymptomatic subjects (1.56 +/- 0.27 vibratory units) and controls (1.63 +/- 0.54 vibratory units). Finger abnormality rates did not differ, although subjects with AIDS or ARC had greater mean vibratory threshold. Subclinical peripheral neuropathy is thus related to stage of HIV infection and is present by quantitative sensory testing in 36% of patients with AIDS or ARC.

AIDS-Related Complex↗
PubMed1992

The nifU, nifS and nifV gene products are required for activity of all three nitrogenases of Azotobacter vinelandii.

Strains with mutations in 23 of the 30 genes and open reading frames in the major nif gene cluster of A. vinelandii were tested for ability to grow on N-free medium with molybdenum (Nif phenotype), with vanadium (Vnf phenotype), or with neither metal present (Anf phenotype). As reported previously, nifE, nifN, nifU, nifS and nifV mutants were Nif- (failed to grow on molybdenum) while nifM mutants were Nif-, Vnf- and Anf-. nifV, nifS, and nifU mutants were found to be unable to grow on medium with or without vanadium, i.e. were Vnf- Anf-. Therefore neither vnf nor anf analogoues of nifU, nifS, nifV or nifM are expected to be present in A. vinelandii.

Azotobacter vinelandii↗
PubMed1992

Changes in retinal pigment epithelial cell autofluorescence and protein expression associated with phagocytosis of rod outer segments in vitro.

The accumulation of autofluorescent lipofuscin was quantified in cultured human retinal pigment epithelial (RPE) cells phagocytosing bovine rod outer segments (BROS) and the expression of proteins in these cells was investigated. Results showed a steady increase in autofluorescence of RPE cells over a 4-week period as measured by fluorophotometric flow cytometry. A significantly greater increase in autofluorescence was found in the cultured RPE cells from a 7-year-old donor compared with those from a 47-year-old donor. Within both groups the BROS-challenged cells had significantly higher fluorescence readings than the control cells which were not challenged. Autoradiography of 35S-labelled proteins separated by polyacrylamide gel electrophoresis (PAGE) revealed a small distinct band at 102 kDa in BROS-challenged RPE cells of both bovine and human origin that did not appear in control or microsphere-phagocytosing RPE cells. The intensity of the signal was unrelated to the duration of the challenge period.

Aging↗
PubMed1992

Quantitative and qualitative analyses of clock drawings in Alzheimer's and Huntington's disease.

Although visuoconstructive impairment has been reported in both Alzheimer's (DAT) and Huntington's (HD) disease, there is little knowledge concerning how this cognitive deficit differs quantitatively and qualitatively in these two progressive dementias. To address this issue, the present study compared performances on the Clock Drawing Test (CDT: command and copy) of 25 DAT patients, 25 equally demented HD patients, and 25 elderly normal controls (NC). In the command condition, both patients groups were significantly impaired compared to the NC group. Although there was no significant difference between DAT and HD patients' total quantitative scores, a qualitative error analysis revealed a number of dissociations between the two patient groups. Graphic difficulties, very common in HD patients, were virtually absent in DAT patients; in contrast, conceptual errors were almost exclusively seen in DAT patients and were related to the severity of their dementia. Perseveration and "stimulus-bound" responses were also more frequent in DAT patients, and both groups made visuospatial errors. In the copy condition, the DAT, but not the HD, patients evidenced a marked improvement in performance. These results indicate that while both DAT and HD patients have significant visuoconstructive difficulties even in the early stages of their disorders, the specific cognitive processes underlying their quantitative impairments are quite different. It is possible that the DAT patients' conceptual errors are yet another indicator of the deterioration of their semantic knowledge.

Aged↗
PubMed1992

Chronic exposure to morphine does not induce dependence at the level of the calcium channel current in human SH-SY5Y cells.

mu-Opioid receptors mediate inhibition of the N-type calcium channel current in the human neuroblastoma cell line SH-SY5Y. We have previously shown that chronic exposure to morphine induces homologous tolerance to this effect. Here we show that chronic incubation with morphine (1 microM for three to seven days) does not, however, induce physical dependence at the level of the calcium channel current. Initial experiments were performed using the whole cell voltage-clamp technique. Chronically treated cells were bathed in superfusate which also contained morphine (1 microM). On washout of morphine the current amplitude increased by 12% and this was reversed by re-addition of morphine. Naloxone (1 microM) elicited a similar increase. However, this increase is most likely due to a reversal of the residual inhibitory effect of morphine on the calcium channel current rather than being a novel withdrawal response. Chronic exposure to morphine did not change the voltage-sensitivity of the calcium channel current or induce the appearance of a current sensitive to the L-type calcium channel agonists Bay K 8644 (3 microM) and S(+)-PN 202-791 (1 microM). In a further series of experiments the nystatin-perforated patch technique was employed in order to prevent washout of any L-type current in these cells. Under these conditions a Bay K 8644-sensitive, L-type current was unmasked following treatment with omega Conus Toxin GVIA. The peak current was depressed by omega Conus Toxin GVIA (1 microM) by approximately 90% both in control cells and cells chronically exposed to morphine. Now Bay K 8644 (3 microM) almost doubled the remaining current but the effect was equal in both groups of cells. It is concluded that chronic exposure to morphine does not induce physical dependence and a withdrawal syndrome in the human SH-SY5Y neuroblastoma cell line by changing either N-type or L-type calcium channel activity.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1992

Analysis of HLA class II allogenotyping in Australian aborigines and Papua New Guinea populations.

Human leukocyte antigen (HLA) class II allogenotyping has been applied to investigate the polymorphism of the DRB, DQB1, DQB2, DQA1, and DQA2 genes in Aborigines from the East Coast of Australia and in Melanesians from the Papua New Guinea North-East Coast and Highlands. Three new DR/DQ arrangements were observed, DRw14/DQB1-2b/DQA1-1a and DRw5Nauru/DQB1-3a/DQA1-2 (n Australian Aborigines), and DRw5Nauru/DQB1-1a/DQA1-1b (in Madang). DQA2 and DQB2 allogenotyping with TaqI and PstI digested genomic DNA revealed little polymorphism among the Papua New Guineans, with DQA2-Xa1 and DQB2-Xb1 the most common alleles in all the groups. However, the presence of DQA2-Xa2 in Papuans and Australian Aborigines reflects the degree of admixture with Caucasoids while the DQA2-Xa4 allele in Madang is probably a marker of Mongoloid origin.

Asian People↗
PubMed1992

Duplex Doppler ultrasound in the investigation of occult nephropathy following haemolytic uraemic syndrome.

Duplex doppler ultrasound has been reported to be of value in the detection of raised vascular resistance, particularly in the renal tract. A prospective single blind study investigating the use of duplex Doppler ultrasound to measure resistive index (RI) in patients with impaired renal function and a history of diarrhoea-associated haemolytic uraemic syndrome (D+ HUS) was performed. There was considerable overlap in the range of RIs, with RIs greater than 70% in children with normal renal function and in those with renal impairment following D+ HUS. There was no significant difference in the mean RI between the groups studied. We feel that the RI is not of value in predicting the presence of occult nephropathy following haemolytic uraemic syndrome.

Child↗
PubMed1979

Systemic sclerosis with subcutaneous nodules.

A case of systemic sclerosis with subcutaneous nodules is described. The nodules consisted of fibrinoid degeneration with surrounding fibrosis, but lacked the typical histiocytic palisade of the rheumatoid nodule. The patient had neither coexistent rheumatoid arthritis nor circulating rheumatoid factor.

Female↗